blinking symbol in upper right corner

While watching movies and series there is an blinking symbol in the upper right corner of the screen. It’s working on my nerves. So I like to know what it is and if I can disable it.

Would you happen to have a screenshot/short movie ?

It might be under-voltage warning indicator, suggesting your power supply is not powerful enough.
It used to be rainbow square, they have hanged it to something else afair.

if its a yellow square its high temperature and a throttled CPU

If its red its a dangerous high temperature

If its more rainbow like your power supply isn´t giving the necessary amps so you should try a better usb charger